US7082023B2 - Method and circuit arrangement for function monitoring of an electronic-mechanical position switch - Google Patents

Method and circuit arrangement for function monitoring of an electronic-mechanical position switch Download PDF

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US7082023B2
US7082023B2 US10/847,168 US84716804A US7082023B2 US 7082023 B2 US7082023 B2 US 7082023B2 US 84716804 A US84716804 A US 84716804A US 7082023 B2 US7082023 B2 US 7082023B2
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output
switching contact
microcontroller
signal
state
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US20040228065A1 (en
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Hans-Juergen Hoegener
Juergen Volberg
Guido Voellmar
Bernd Wolff
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Eaton Industries GmbH
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Moeller GmbH
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H9/00—Details of switching devices, not covered by groups H01H1/00 - H01H7/00
    • H01H9/54—Circuit arrangements not adapted to a particular application of the switching device and for which no provision exists elsewhere
    • H01H9/547—Combinations of mechanical switches and static switches, the latter being controlled by the former
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
    • G01D5/14—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage
    • G01D5/16—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying resistance
    • G01D5/165—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying resistance by relative movement of a point of contact or actuation and a resistive track

Definitions

  • the invention relates to a method and to a circuit arrangement for function monitoring of an electronic-mechanical position switch wherein a microcontroller detects a wiper potential that is present at the wiper of a potentiometer, evaluates the wiper potential in comparison to a stored threshold value and, depending on whether the wiper potential exceeds or falls below the threshold value, at least one switching contact is closed or opened via a control signal.
  • the product information no. W 13-7364, 4/1996 of the Klöckner-Moeller Company titled “Monitoring and detecting: reliable and safe, position switch AT” describes an electromechanical position switch.
  • a housing there are mechanical switching contacts, for example, pairs of or individual contacts of break contacts and/or make contacts, and there is a butt tappet that can be slid lengthwise for direct mechanical actuation of the switching contacts.
  • replaceable drive heads are placed in front of the butt tappets.
  • a drive head with a swiveling lever, a roller lever, an adjustable roller lever or a torsion bar can be attached to the housing of the position switch.
  • An electronic-mechanical position switch is known from German utility model DE 202 03 214 U1.
  • An actuation tappet, a potentiometer, a microcontroller and electronic switching contacts are arranged in a housing.
  • the actuation tappet is coupled to the wiper of the potentiometer.
  • a changing electric signal is fed to the microcontroller and this signal brings about a change in the state of the switching contacts when the signal exceeds or falls below a programmed threshold value.
  • the switching contacts are connected to the clamp terminals on the output side.
  • the threshold value In order to set the switch-over point, it is proposed to program the threshold value via a programming connection or via a selector switch, or else to make a selection from a number of predetermined threshold values that are stored in a microcontroller. No information is provided as to how failures in the electronic system can be detected in order to prevent erroneous output signals from leading to erroneous control operations at the periphery of the position switch.
  • German patent DE 37 34 431 C2 describes a method for monitoring the state transition of final stage circuits for final control elements from the closed to the open state.
  • the trip-on signals are periodically interrupted by test signals.
  • Feedback to a microcomputer is sent from the final stage circuits and, if the state transition does not occur, said microcomputer ensures that the final stage circuits are permanently set to the open state.
  • the test signals are shorter than the response-reaction time of the final control elements.
  • the microcomputer is not monitored.
  • an object of the present invention is to provide a method for monitoring the function of an electronic-mechanical position switch.
  • the present invention provides a method for function monitoring of an electronic-mechanical position switch, the electronic-mechanical position switch including: a housing; an actuation tappet; a potentiometer configured to be acted upon by the actuation tappet; an electronic switching contact; a microcontroller configured to emit dynamically-changing watchdog signals and to detect a wiper potential present at a wiper of the potentiometer, compare the wiper potential to a stored threshold value and, depending on whether the wiper potential is above or below the threshold value, trigger a closing or opening of the electronic switching contact via a control signal; a power supply device; and a clamp terminal.
  • the method includes the consecutive steps:
  • the present invention also provides a switching arrangement for function monitoring of an electronic-mechanical position switch, the switching arrangement comprising:
  • the method according to the invention tests the watchdog monitoring on the one hand and the current-breaking capacity of the at least one electronic switching contact on the other hand.
  • the watchdog monitoring serves to detect failures of the microcontroller and to reliably cause the switching contact to make the transition to the open state in order to avoid erroneous control operations at the periphery of the position switch.
  • the microcontroller generates watchdog signals whose absence would indicate a failure of the microcontroller.
  • the term “current-breaking capacity” means that when the tappet passes the switch-over point in the appropriate direction, the switching contact that had been closed until then does indeed open.
  • the process steps A and B are carried out as a precautionary measure to determine whether an absence of the watchdog signals is indeed detected by the switching means that are monitoring the watchdog signals.
  • the process steps C and D are carried out to determine whether the switching contact that is in the closed state is capable of being opened. In case of proper functioning, the closed state of the electronic switching contact is effectuated by the closing signal level of the control signal.
  • a component failure can occur on the way from the output of the microcontroller to the switching contact, as a result of which the switching contact can no longer assume the open state, for example, as a result of the fusing of the output electrodes of the electronic switching contact.
  • Such failures have to be detected at an early point in time since in some cases, the actuation tappet does not pass through the switching point for a long time.
  • the first and second test intervals which are essentially determined by material-related and program-related delay times during which the closed switching contact is briefly opened—are of short duration (typically 200 ⁇ s to 400 ⁇ s) and thus do not have a perceptible effect on the periphery of the position switch.
  • the first and the second test intervals occur at periodical intervals, preferably after a time interval comprising 500 to 1200 program cycles of the microcontroller, which corresponds to a test period of 2 to 6 seconds.
  • An advantageous embodiment of the process according to the invention consists in that, in order to shield off coincidental disturbances, the switching contact is permanently open only in case of the repeated absence of the expected state transition of the switching contact during the first or the second test interval, that is to say, only after the repeated execution of process steps A through D.
  • Another advantageous embodiment consists in that, in order to improve the function monitoring, the logical state predefined by the microcontroller is additionally compared by checking back with the actual physical state of the at least one switching contact and in that, if there is no correspondence, the control signal assumes the opening signal level and the watchdog signals are not emitted.
  • the microcontroller In response to erroneous watchdog monitoring, to an absent current-breaking capacity or to an illogical output state, it is advantageous for the microcontroller to emit an error message signal, for example, in order to actuate an LED display installed in the housing.
  • the watchdog monitoring as well as the current-breaking capacity of the at least one electronic switching circuit are checked in order to their hardware functions.
  • An active time stage detects watchdog signals coming from the microcontroller and assumes different output states, depending on whether dynamically changing watchdog signals are present or not. If watchdog signals are present, the time stage activates a supply driver to apply a supply potential to at least one output circuit containing the at least one switching contact. With the start of the first test intervals, the microcontroller switches off the watchdog signals, in response to which the time stage deactivates the supply driver in order to disconnect the output circuit from the supply potential. If the switching contact was previously in the closed state, then, if the time stage and the supply driver are intact, it makes the transition to the open state. The output of the switching contact is fed back to the microcontroller for purposes of being checked against the expected logical result.
  • the microcontroller After the detection of the proper state transition, the microcontroller once again emits watchdog signals, in response to which the time stage once again activates the supply driver so that the supply potential passes through and the briefly opened switching contact closes again.
  • the watchdog monitoring is disrupted, that is to say, if the expected state transition does not occur, then the switching contact is inevitably opened via the output circuit by setting the control signal to the opening signal level.
  • the control signal provided by the microcontroller if by then it has assumed the closing signal level—makes the transition to the opening signal level.
  • the microcontroller After the microcontroller has read in the proper state transition from the fed back output of the switching contact, it once again closes the briefly opened switching contact by reducing the opening signal level.
  • the switching contact is inevitably opened via the time stage and via the supply driver by switching off the watchdog signals.
  • the duration (typically 200 ⁇ s to 400 ⁇ s) of the opening of the at least one switching contact for testing purposes is essentially determined by material-related and program-related delay times of the circuit arrangement and does not have a perceptible effect on the periphery of the position switch.
  • An advantageous embodiment of the switching arrangement according to the invention consists in that the time stage is consecutively made up of a first and a second amplifier stage having a passive differentiating element or an integrating element at the input.
  • the output state of the first amplifier stage likewise changes dynamically, with the result that the integrating element cannot be charged or discharged to a threshold level, as a result of which the second amplifier stage remains in the first output state.
  • the first amplifier stage assumes a defined state, with the result that the integrating element exceeds or falls below the threshold level and consequently the second amplifier stage makes the transition to the second output state.
  • FIG. 1 a block diagram of an electronic-mechanical position switch operated using the method according to the invention
  • FIG. 2 a flow chart of the method according to the invention
  • FIG. 3 a representation of a switching arrangement according to the invention
  • FIGS. 4–7 examples of signal diagrams pertaining to the invention.
  • the electronic-mechanical position switch 2 is set up in a box-like housing 4 that is, however, only indicated in rudimentary form.
  • the housing 4 contains an actuation tappet 8 that can be moved in the actuation direction Y along with or opposite to the spring force of a pressure spring 6 as well as a wiper 10 of a potentiometer R 1 , said wiper being coupled to said actuation tappet 8 .
  • the housing 4 also contains conventional power supply means 14 , a microcontroller 16 , a first and a second output circuit 18 or 19 , monitoring switching means 20 , an LED display H 1 and an acknowledgement key S 1 .
  • the electronic components are attached to a printed circuit board or to two printed circuit boards joined together.
  • the acknowledgement key S 1 is configured as a DIP switch. Via a pair of first clamp terminals 26 , an input voltage Ve is supplied that is converted by means of the power supply means 14 into a positive first supply potential Vbb and into a second positive supply potential Vdd that is lower than the first.
  • the supply potentials Vbb and Vdd refer to the reference potential GND (ground potential).
  • the output circuits 18 and 19 which each contain a first and a second electronic switching contact N 1 or N 2 , are fed via the switching means 20 with the first supply potential Vbb and the microcontroller 16 is fed directly with the second supply potential Vdd.
  • replaceable drive heads can be installed in front of the actuation tappet 8 .
  • the position of the actuation tappet 8 is transferred to the wiper 10 of the potentiometer R 1 .
  • a different wiper potential Vs is present at the wiper 10 .
  • the wiper potential Vs that refers to the reference potential GND is converted by the microcontroller 16 into a digital value and compared to a stored threshold value Vr.
  • an external voltage Va supplied by the microcontroller 16 , is applied to the two external connections 34 and 36 of the potentiometer R 1 .
  • the microcontroller 16 emits control signals V 1 and V 2 whose signal levels depend on whether the value of the wiper potential Vs lies above or below the threshold value Vr.
  • the control signals V 1 and V 2 as a function of the wiper position X and depending on whether the electronic switching contacts N 1 and N 2 as such are to function as a make contact or as a break contact, the switching contacts N 1 and N 2 are regulated into the closed or open state.
  • the determination of whether the contacts N 1 and N 2 are functioning as a break contact or as a make contact is made by programming the microcontroller 16 .
  • the driver output Q 1 or Q 2 is blocked in case of a break contact, but said driver output Q 1 or Q 2 is conductively connected to the first supply potential Vbb in case of a make contact.
  • the corresponding driver output Q 1 or Q 2 is conductively connected to the first supply potential Vbb in the case of a break contact, but it is non-conductive in the case of a make contact.
  • the driver outputs Q 1 and Q 2 are connected with a pair of second clamp terminals 28 to which electric and/or electronic peripheral devices are connected that are to be actuated by the position switch 2 .
  • the acknowledgement key S 1 connected to the microcontroller 16 serves to set a desired position of the actuation tappet 8 as the new switch-over point of the position switch 2 in that, by actuating the acknowledgement key S 1 , the appertaining wiper potential Vs is taken in the microcontroller 16 as the new determining threshold value Vr.
  • the microcontroller 16 emits different signals to the LED display H 1 in order to indicate errors, confirmations and certain states by lighting up or blinking at different blinking frequencies.
  • the monitoring switching means 20 serves to monitor the proper functioning of the microcontroller 16 and monitors the watchdog signals Vw emitted by the microcontroller 16 .
  • FIG. 2 In order to explain the method according to the invention for function monitoring of the electronic-mechanical position switch 2 according to FIG. 1 , reference will be made below to FIG. 2 , whereby it is assumed that at least one of the switching contacts N 1 , N 2 is in the closed state.
  • the logical values “0” or “1”, in conjunction with the control signals V 1 and V 2 mean that the appertaining switching contacts N 1 and N 2 are to assume the closed or open state, depending on the specific wiper position X and on the threshold value Vr.
  • the microcontroller 16 emits watchdog signals Vw that change dynamically at brief, irregular intervals between two logical states.
  • a failure of the microcontroller 16 is simulated by means of programmed discontinuation of the watchdog signals Vw.
  • the subsequent process step B checks whether the absence of the watchdog signals Vw is detected by the monitoring switching means 20 . If the watchdog monitoring by the switching means 20 is intact and if the watchdog signals Vw are absent, then the switching contact N 1 and/or N 2 , if it was previously in the closed state, has to make the transition to the open state due to the removal of its power supply, the first supply potential Vbb.
  • this state transition which was recognized by the microcontroller 16 , leads to the termination of the first test interval ⁇ t 1 and to the resumption of the emission of watchdog signals Vw.
  • the appertaining control signal V 1 and/or V 2 is set so as to open the switching contacts N 1 and/or N 2 .
  • the at least one switching contact N 1 and/or N 2 permanently makes the transition to the open state.
  • the emission of watchdog signals Vw continues to be absent.
  • step C which is time-staggered with respect to process step A, when a second test interval ⁇ t 2 begins, a switch-over point of the at least one control signal V 1 and/or V 2 into the opening state is simulated, if said signal had been at the closing signal level until then.
  • step D the current-breaking capacity of the appertaining switching contact N 1 , N 2 is tested in conjunction with the appertaining output circuit 18 or 19 . If the current-breaking capacity is intact, the switching contact N 1 and/or N 2 that had been closed until then has to make the transition to the open state due to the change of the appertaining control signal V 1 and/or V 2 .
  • this state transition which was recognized by the microcontroller 16 , leads to the termination of the second test interval ⁇ t 2 and to the control signal V 1 and/or V 2 being switched back to the closing signal level.
  • the emission of the watchdog signals Vw is terminated and the output of the switching contact N 1 and/or N 2 that has subsequently been disconnected from its power supply functions as an open contact at the periphery of the position switch.
  • the at least one control signal V 1 , V 2 continues to assume the opening signal level.
  • the process step E tests whether the physical output state of the switching contacts N 1 and N 2 corresponds to the logical default value from the microcontroller 16 .
  • the function monitoring is continued with the process steps A to E.
  • the control signal V 1 and/or V 2 which so far had assumed the closing signal level, is set to open and the emission of the watchdog signals Vw is terminated.
  • the method according to the invention ensures that a negative test result in one of the process steps B, D or E causes the electronic switching contacts N 1 and N 2 to be inevitably opened, both by terminating the emission of watchdog signals Vw as well as by setting or halting the control signals V 1 and V 2 at the opening signal level.
  • the pertinent safety regulations are met which require that, in case an electromechanical or an electronic-mechanical position switch should fail, the switching contacts must not assume the active, that is to say, closed state.
  • FIG. 3 In order to explain the switching arrangement according to the invention, reference is made below to FIG. 3 .
  • the reference numerals employed before in FIG. 1 are used for the same function elements.
  • the reference potential GND or the second supply potential Vdd at a value of +5V relative to the reference potential GND is supplied to the microcontroller 16 at its connections VSS and VDD.
  • the external connections of the potentiometer R 1 are supplied with an external voltage via the outputs PTB 0 and PTB 1 of the microcontroller 16 .
  • the wiper voltage Vs is fed to an analog input ADO of the microcontroller 16 .
  • the acknowledgement key S 1 connects the second supply potential Vdd to a voltage divider R 14 , R 15 leading to the reference potential and whose dividing point is connected to an input PTB 7 of the microcontroller 16 .
  • the control signals V 1 and V 2 emitted at the control outputs PTB 5 and PTB 3 of the microcontroller 16 serve to control the output circuits 18 and 19 .
  • the output circuit 18 or 19 consists of the electronic switching contact N 1 or N 2 as well as of an upstream threshold value switch.
  • the threshold value switch that is upstream from the switching contact N 1 or N 2 is provided with an NPN transistor T 7 or T 10 in an emitter circuit.
  • a Z-diode Z 1 or Z 2 and a voltage divider R 19 , R 20 or R 8 , R 9 are located upstream from the transistor T 7 or T 10 .
  • the transistor T 7 or T 10 is connected to a load resistor R 21 or R 25 and to the input IN of the switching contact N 1 or N 2 .
  • the driver outputs Q 1 , Q 2 of the switching contacts N 1 , N 2 serve to actuate electric devices at the periphery of the position switch 2 .
  • the supply connections VBB of the output circuits 18 , 19 are supplied via a supply driver N 3 with the first supply potential Vbb at a value of, for example, +30V.
  • the control signal V 1 or V 2 has assumed the closing signal level, that is to say, the high level, then the switching contact N 1 or N 2 in question is in the closed state. In this case, a high level leading to the reference potential is present at a peripheral load that is connected to the driver output Q 1 or Q 2 , said high level being somewhat below the first supply potential Vbb.
  • the switching contact N 1 or N 2 in question is in the open state.
  • a low level leading to the reference potential is present at a peripheral load that is connected to the driver output Q 1 or Q 2 , said low level being identical to the reference potential GND.
  • the microcontroller 16 used is a commercially available microcontroller bearing the model designation M68HC908QY4 made by Motorola Inc. and the electronic switching contacts N 1 , N 2 as well as the supply driver N 3 are commercially available circuits sold by Infineon Technologies AG and bearing the model designation BTS 4140 N which, on the output side, contain a vertical N-channel-power MOSFET.
  • the microcontroller 16 emits watchdog signals Vw that dynamically change in short, not necessarily regular intervals between two logical state levels, until these signals stop at the beginning of the first test intervals.
  • a subsequent active time stage 22 assumes different output states, depending on whether dynamic watchdog signals Vw are present or not.
  • the time stage 22 contains a first amplifier stage 30 with a PNP transistor T 9 in a collector circuit whose emitter is connected to the second supply potential Vdd.
  • the time stage 22 is provided with a passive differentiating element 23 , consisting of the series connection of a first capacitor C 9 , a resistor R 27 and a resistor R 23 leading to the second supply potential Vdd.
  • the connection point of the resistors R 23 , R 27 that function as voltage dividers is connected to the base of the transistor T 9 .
  • the first amplifier stage 30 works together with a passive integrating element 24 .
  • the integrating element 24 consists of the series connection of a resistor R 29 on the collector side and of a parallel circuit leading to the reference potential, of a second capacitor C 8 and of two series-connected discharge resistors R 5 , R 6 .
  • a second amplifier stage 31 contains an NPN transistor T 5 in a collector circuit and the integrating element 24 on the input side.
  • the transistor T 5 is connected via its emitter to the reference potential, via its base to the connection point of the resistors R 8 , R 9 and via its collector to a load resistor R 24 leading to the first reference potential Vbb.
  • Dynamic watchdog signals Vw present on the input side at the differentiating element 23 of the time stage 22 bring about a brief recharging of the second capacitor C 8 via the first amplifier stage 30 during each transition from high level to low level, so that, at the connection point of the discharge resistors R 5 , R 6 , a potential is maintained that keeps the transistor T 5 in the conductive state with a low level at the collector.
  • the conductive state of the transistor T 5 corresponds to a first output state of the time stage 22 . If dynamic watchdog signals Vw are absent, the transistor T 9 remains blocked so that, as a result of increasing discharging of the second capacitor C 8 , the transistor T 5 goes into the blocked state with a high level at the collector.
  • the blocked state of the transistor T 5 corresponds to a second output state of the time stage 22 .
  • the time constants of the differentiating element 23 as well as of the integrating element 24 are selected in such a way that the time stage 22 — due to the occurrence of an individual watchdog signal—would assume the first output state and, with a delay, would fall back to the second output state.
  • the time stage 22 is kept in the first output state through dynamic, that is to say, constantly changing watchdog signals Vw, as a result of which the subsequent supply driver N 3 is activated.
  • watchdog signals Vw are absent, the time stage 22 toggles to the second output state, as a result of which the supply driver N 3 is deactivated.
  • dynamic watchdog signals Vw are emitted once again, the time stage toggles back to the first output state.
  • the supply driver N 3 conducts the first supply potential Vbb that is present at its supply input VBB virtually undiminished to the output circuits 18 and 19 via its driver output Q 3 .
  • the switching contact N 1 or N 2 depending on the logical default value from the control signal V 1 or V 2 emitted by the appertaining microcontroller 16 , can assume the closed (i.e. conductive) state or the open (i.e. blocked) state.
  • the supply driver N 3 disconnects the output circuits 18 , 19 from the first supply potential Vbb, whereby, due to the resistor R 22 leading to the reference potential, the driver output Q 3 assumes the reference potential GND.
  • the switching contact N 1 or N 2 independent of the logical default value from the microcontroller 16 , indicates a state that is recognized by the periphery of the position switch 2 as being open. Therefore, if the watchdog signals Vw are absent, either intentionally during testing within the scope of first test intervals or else as a result of a failure of the microcomputer 16 , the switching contact N 1 and/or N 2 , if it was previously in the closed state, should make the transition to the open state.
  • the output Q 1 or Q 2 of the switching contact N 1 or N 2 is actively connected via an additional amplifier stage 32 or 33 to a control input PTB 6 or PTB 4 of the microcontroller 16 which, during the first test intervals, internally checks the state of the switching contacts N 1 and N 2 against the expected logical result.
  • the additional amplifier stage 32 contains an NPN transistor T 8 in an emitter circuit. The transistor T 8 is connected via its emitter to the reference potential, via its collector to the control input PTB 6 as well as to a load resistor R 28 leading to the second reference potential Vdd. The base of the transistor T 8 is connected via a series resistor to the output Q 1 .
  • the series resistor R 18 forms an interference-suppression element for suppressing brief signal transitions that occur due to internal or external interferences and that can otherwise cause erroneous evaluations by the microcomputer 16 .
  • the additional amplifier stage 33 connected to the drive output Q 2 likewise consists of an NPN transistor T 6 in an emitter circuit, a load resistor R 10 and an interference-suppression element 33 which, in turn, consists of a capacitor C 5 , a discharge resistor R 12 and a series resistor R 13 .
  • the switching contact N 1 and/or N 2 which was closed before the first test interval—makes the proper transition to the open state. If the microcontroller 16 recognizes the expected state transition via its control input PTB 6 and/or PTB 4 , said microcontroller 16 once again emits dynamic watchdog signals Vw via its output PTB 2 . Then the time stage 22 toggles back to the first output state and releases the first supply potential Vbb for the output circuits 18 and 19 , in response to which the briefly opened switching contact N 1 and/or N 2 once again assumes its closed state.
  • the interruption of the closed state of the switching contact N 1 and/or N 2 that occurred is not long enough that it could have been perceived by a consumer that is connected to the driver output Q 1 or Q 2 .
  • the watchdog monitoring is faulty, that is to say, in case of a defect of the time stage 22 and/or of the supply driver N 3 , during which the output circuits 18 and 19 are not disconnected from the first supply potential Vbb during the first test interval, the microcontroller 16 cannot receive the expected state transition of the switching contact N 1 and/or N 2 at its control input PTB 6 and/or PTB 4 , either.
  • the microcontroller 16 still does not emit watchdog signals Vw, and at the same time, it sets the control signal V 1 and/or V 2 belonging to the switching contact N 1 and/or N 2 to the state level that causes the switching contact N 1 and/or N 2 to make the transition to the open state, and it supplies an error message to the LED display H 1 via its output AD 1 .
  • a defect of the time stage 22 and/or of the supply driver N 3 should manifest itself in the fact that, in spite of the presence of watchdog signals Vw, the output circuits 18 and 19 are disconnected from the first supply potential Vbb, then in this case, of course, both switching contacts N 1 and N 2 are opened. Consequently, in any case, a defect in the watchdog monitoring leads to an inevitable opening of the electronic switching contacts N 1 , N 2 .
  • the switching arrangement according to the invention shown in FIG. 3 also allows the current-breaking capacity of the output circuits 18 and 19 to be checked, especially that of the electronic switching contacts N 1 and N 2 .
  • the closing control signal V 1 and/or V 2 emitted by the microcontroller 16 is switched over from the high level to the low level. If the output circuit 18 or 19 is intact, this should cause the previously closed switching contact N 1 and/or N 2 to make the transition to the open state.
  • This state transition is, in turn, read into the microcontroller 16 from the driver output Q 1 and/or Q 2 via the already described additional amplifier stage 32 or 33 and internally compared to the expected test state.
  • control signal V 1 and/or V 2 is once again reset to the closing signal level by the state transition that occurs at the control input PTB 6 and/or PTB 4 during the second test intervals.
  • the interruption of the closed state of the switching contact N 1 and/or N 2 that has occurred is also so brief here as well that it could not be perceived by a consumer connected to the driver output Q 1 or Q 2 .
  • the output circuit 18 and/or 19 has lost its current-breaking capacity due to a defect, especially as a result of the fusing of the output path of the electronic switching contact N 1 and/or N 2 .
  • the appertaining driver output Q 1 or Q 2 does not report a state change from the closed state to the open state back to the control input PTB 6 or PTB 4 .
  • the microcontroller 16 does not set the control signal V 1 or V 2 back to the closing signal level. Instead, further emission of watchdog signals Vw via the output PTB 2 to the time stage 22 does not occur, which results in a disconnection of the output circuits 18 , 19 from the first supply potential Vdd and thus an inevitable opening of the switching contacts N 1 , N 2 .
  • the microcontroller 16 supplies a corresponding error message to the LED display H 1 .
  • the microcontroller 16 can also check whether the logical state at the signal outputs PTB 5 and PTB 3 — which is determined by the wiper potential Vs in conjunction with the set threshold value Vr—corresponds to the state at the driver outputs Q 1 and Q 2 . If there is no correspondence, for example, due to a defect in one of the output circuits 18 or 19 or in one of the additional switching stages 32 or 33 , then a program of the microcontroller 16 sets the control signals V 1 , V 2 at the opening signal level and the watchdog signals Vw are switched off. Here, too, the electronic switching contacts N 1 , N 2 are inevitably opened. In this case as well, the microcontroller 16 supplies a corresponding error report signal to the LED display H 1 .
  • FIGS. 4 to 7 serve to provide an additional explanation of the method according to the invention shown in FIG. 2 as well as of the switching arrangement according to the invention shown in FIG. 3 .
  • the first switching contact N 1 functions as a make contact
  • the second switching contact N 2 functions as a break contact. It is also assumed that, at the switch-over point in time to, the switch-over point is passed by the actuation tappet 8 .
  • the first control signal V 1 should make the transition from the low level to the high level and thus the first driver output Q 1 belonging to the first switching contact N 1 should make the transition from the open state (low level) to the closed state (high level).
  • the second control signal V 2 should make the transition from the high level to the low level and thus the second driver output Q 2 belonging to the second switching contact N 2 should make the transition from the closed state (high level) to the open state (low level).
  • FIG. 4 shows signal sequences under the assumption that no failures have occurred.
  • the watchdog signals Vw following each other at close but not necessarily regular intervals change dynamically between the low level and the high level.
  • the watchdog signals Vw are interrupted, as a result of which the third driver output Q 3 belonging to the supply driver N 3 drops from the high level (virtually at the value of the first supply potential Vbb) to the low level (reference potential).
  • the second control signal V 2 has assumed the closing high level before the switch-over point in time to, due to the absence of a power supply, the second driver output Q 2 briefly assumes the low level during the first test intervals ⁇ t 1 .
  • This state transition at the second driver output Q 2 each time successfully terminates the first test intervals ⁇ t 1 when watchdog signals Vw are emitted once again.
  • the first driver output Q 1 of the open first switching contact N 1 assumes the low level, irrespective of the first test intervals ⁇ t 1 .
  • the first control signal V 1 has assumed the closing high level. Due to the absence of a power supply during the first test intervals ⁇ t 1 , the first driver output Q 1 briefly assumes the low level. In this case, this state change at the first driver output Q 1 each time successfully terminates the first test intervals ⁇ t 1 .
  • the second driver output Q 2 of the now open second switching contact N 2 has assumed the low level, irrespective of the first test intervals ⁇ t 1 .
  • watchdog signals Vw are emitted once again and the switching contacts N 1 and N 2 are supplied with power via the third driver output Q 3 (high level).
  • the closing second control signal V 2 is set to the low level in order to check the current-breaking capacity, as a result of which the second driver output Q 2 drops to the low level. This state transition at the second driver output Q 2 each time successfully terminates the second test intervals ⁇ t 2 when the second control signal V 2 is reset once again to the closing signal level (high level).
  • the first driver output Q 1 Before the switch-over point in time t 0 , the first driver output Q 1 has assumed the low level, irrespective of the second test intervals ⁇ t 2 .
  • the closing first control signal V 1 After the switch-over point in time t 0 , during the second test intervals ⁇ t 2 , the closing first control signal V 1 is set to the low level, as a result of which the first driver output Q 1 drops to the low level. In this case, this state transition at the first driver output Q 1 each time successfully terminates the second test intervals ⁇ t 2 when the first control signal V 1 is reset once again to the closing signal level (high level).
  • the second driver output Q 2 After the switch-over point in time to, the second driver output Q 2 has assumed the low level, irrespective of the second test intervals ⁇ t 2 .
  • the state transition at the second driver output Q 2 that did not occur leads to a situation in which, at a point in time t 1 ′ with a small, system-related delay vis-à-vis the point in time t 1 , the second control signal V 2 is permanently set at the opening state level (low level).
  • the appertaining test interval ⁇ t 1 cannot be terminated and thus the emission of watchdog signals Vw cannot be resumed again either.
  • the transition of the first control signal V 1 to the closing signal level does not occur.
  • the position switch 2 is in a standby condition.
  • the state transition at the first driver output Q 1 that did not occur leads to a situation in which, at a point in time t 2 ′ with a small, system-related delay vis-à-vis the point in time t 2 , the watchdog signals Vw are permanently absent. Then the third driver output Q 3 , after a point in time t 2 ′ that is slightly delayed vis-à-vis the point in time t 2 ′′, no longer supplies power to the switching contacts N 1 and N 2 , as a result of which the first driver output Q 1 inevitably assumes the low level corresponding to the open state. The appertaining test interval ⁇ t 2 cannot be terminated and consequently the control signals V 1 and V 2 can no longer assume the closing signal level (high level) either. In this case as well, the position switch 2 is in a standby condition.
  • the cause is to be sought in a defect of the output circuit 18 ( FIGS. 1 and 3 ) that contains the first switching contact N 1 or in a defect of the additional amplifier stage 32 ( FIG. 3 ) that leads from the first driver output Q 1 back to the microcontroller 16 .
  • the ascertained contradiction between the first control signal V 1 and the signal level of the first driver output Q 1 leads to a situation in which, after a point in time t 3 ′ with a small, system-related delay vis-à-vis the point in time t 3 , the watchdog signals Vw are absent and the second control signal V 2 is set at the opening signal level (low level). Then all three driver outputs Q 1 to Q 3 assume the low level. In this case as well, the position switch 2 is in a standby condition.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Debugging And Monitoring (AREA)
  • Keying Circuit Devices (AREA)
  • Rotary Switch, Piano Key Switch, And Lever Switch (AREA)
  • Radar Systems Or Details Thereof (AREA)
US10/847,168 2003-05-17 2004-05-17 Method and circuit arrangement for function monitoring of an electronic-mechanical position switch Expired - Fee Related US7082023B2 (en)

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DEDE10322385.1 2003-05-17
DE10322385A DE10322385B3 (de) 2003-05-17 2003-05-17 Verfahren und Schaltungsanordnung zur Funktionsüberwachung eines elektronisch- mechanischen Positionsschalters

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EP (1) EP1480239B1 (pl)
AT (1) ATE488849T1 (pl)
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Cited By (2)

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US20060158485A1 (en) * 2005-01-18 2006-07-20 Hill Gregory S Power switch system
US20080148109A1 (en) * 2006-12-18 2008-06-19 Bashor Paul D Implicating multiple possible problematic components within a computer system using indicator light diagnostics

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DE102004017692A1 (de) * 2004-04-10 2005-11-10 Moeller Gmbh Verfahren zum Betreiben eines mechanisch-elektronischen Positionsgebers
DE102016004525A1 (de) * 2016-04-14 2017-10-19 Andreas Stihl Ag & Co. Kg Verfahren und Vorrichtung zur Erkennung der Schaltstellung eines Betriebsschalters zur Inbetriebnahme eines Elektromotors
CN111263895B (zh) 2017-10-23 2022-02-22 阿尔卑斯阿尔派株式会社 异常检测装置以及异常检测方法
DE102020205141A1 (de) 2020-04-23 2021-10-28 Zf Friedrichshafen Ag Überwachung eines Betriebsartenwahlschalters
CN114005400B (zh) * 2021-10-29 2024-02-27 昆山国显光电有限公司 像素电路和显示面板

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US20060158485A1 (en) * 2005-01-18 2006-07-20 Hill Gregory S Power switch system
US20080148109A1 (en) * 2006-12-18 2008-06-19 Bashor Paul D Implicating multiple possible problematic components within a computer system using indicator light diagnostics

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DE10322385B3 (de) 2004-11-11
US20040228065A1 (en) 2004-11-18
PL1480239T3 (pl) 2011-05-31
DE502004011890D1 (de) 2010-12-30
EP1480239B1 (de) 2010-11-17
DK1480239T3 (da) 2011-03-07
EP1480239A3 (de) 2006-06-07
PT1480239E (pt) 2011-01-28
ES2357398T3 (es) 2011-04-26
EP1480239A2 (de) 2004-11-24
ATE488849T1 (de) 2010-12-15

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